Showing papers on "Uca pugilator published in 1983"

Female choice in the resource-defense mating system of the sand fiddler crab, Uca pugilator

Abstract: Mating preferences of individual females and mating patterns among marked crabs were studied during the summers of 1973–1976 on sand beaches in mangrove habitat on the west coast of Florida in order to determine if females choose mates indirectly on the basis of the quality of a resource males defend and females use during breeding, directly on the basis of male size, or both.

A collagenolytic serine protease with trypsin-like specificity from the fiddler crab Uca pugilator

Abstract: A second collagenolytic serine protease has been isolated from the hepatopancreas of the fiddler crab, Uca pugilator. This enzyme cleaves the native triple helix of collagen under physiological conditions of pH, temperature, and ionic strength. In addition to its collagenolytic activity, the enzyme exhibits endopeptidase activity toward other polypeptides and small molecular weight synthetic substrates. The polypeptide bond specificity of this enzyme is similar to that of bovine trypsin as is its interaction with specific protease inhibitors. The amino-terminal sequence of this enzyme displays significant homology with other serine proteases, most notably with that of crayfish trypsin, and demonstrates that this enzyme is a member of the trypsin family of serine endopeptidases. The relatively unique action of this protease with regard to both collagenous and noncollagenous substrates has important implications concerning the specificity and mechanism of collagen degradation.

Partial characterization of eyestalk hormones controlling molt and gonadal development in the spiny lobster panulirus argus

Abstract: The eyestalk neurosecretory system of Crustacea contains several peptide factors affecting various important physiological processes. Gonad inhibiting hormone (GIH) and a molt inhibiting hormone (MIH) have been separated and partially characterized using Sephadex gel chromatography and polyacrylamide gel electrophoresis. The eyestalks of the spiny lobster Panulirus argus were the source for these isolations, and activity was bioassayed in the fiddler crab Uca pugilator. Gonad inhibiting hormone has an apparent molecular weight near 5,000 daltons. Molt inhibiting hormone does not induce gonadal inhibition in fiddler crabs, but it does delay the onset of the molt cycle in eyestalkless crabs. Melanin dispersion in intact Uca pugilator was inversely correlated with gonadal growth.

Methylmercury effects on regeneration and ecdysis in fiddler crabs (Uca pugilator, U. pugnax) after short-term and chronic pre-exposure

Abstract: Methylmercury (meHg) inhibits limb regeneration and molting in fiddler crabs. The present study shows that, inUca pugilator from a clean site, the inhibitory effects of 0.5 Μg/ml meHg were unaffected by short term pre-exposure to low levels (0.06 or 0.1 Μg/ml) of meHg under laboratory conditions. Chronic exposure tests onUca pugnax showed that the inhibitory effects of meHg varied with the sex of the crabs and the level of contamination at the site of collection. These effects were less pronounced in crabs from an area subjected to heavy metal pollution (Piles Creek, Linden, NJ) than in crabs from a relatively cleaner area (Big Sheeps-head Creek, Tuckerton, NJ). The order of susceptibility to meHg according to its interaction with sex and site from least susceptible to most was: Piles Creek females, Piles Creek males, Tuckerton males, Tuckerton females. Residue analysis showed that all groups absorbed equivalent amounts of mercury, but only the females from Piles Creek were able to depurate to near control levels after two weeks in clean water.

The roles of hemocytes in tanning during the molting cycle: a histochemical study of the fiddler crab, uca pugilator

Abstract: Histochemical data support the previous biochemical finding that the blood is a major site for the production of proteinaceous and diphenolic substances for tanning of the cuticle in the fiddler crab, Uca pugilator. Five types of hemocytes are described. Specifically in tanning, the hyaline cells (cystocytes) appear responsible for the production of diphenolic tanning agents whereas the granulocytes synthesize the proteins involved. Other types of hemocyte may be transitional forms involved in clotting (intermediate cells). Various histochemical reactions for each type of hemocyte and the cuticle are recorded throughout the molting cycle, and appear cyclic. The data suggest there is hormonal control of the cyclic events during the tanning process.

Vibration transmission through the walking legs of the fiddler crab,Uca pugilator (Brachyura, Ocypodidae) as measured by Laser Doppler Vibrometry

Abstract: 1 Substrate-borne vibration signals play an important role in the life of the fiddler crabUca pugilator In this study we investigated how a vibration signal is transmitted through the legs and body of the freely standing live crab and how it is modified on its way to the sites of the crab's vibration-receptive organs 2 An optical technique, Laser Doppler Vibrometry (LDV), was used to measure the motion of the substrate (the input signal) and the motion of the dactylopodite, carpopodite, meropodite and carapax (the output signals) The output motion was compared with the input motion to determine the transfer function at each of the measured points over the frequency range of 10 to 1,000 Hz 3 In response to a single input vibration pulse with an energy spectrum similar to that of a rap of a male fiddler crab, points on the crab showed amplification of the low-frequency components (up to 25–250 Hz) with no amplification or else attenuation in a mid-frequency range (from 25–250 to about 800 Hz), and then a range of less attenuation or slight amplification above about 800 Hz (Fig 4) The amplification and attenuation effects tended to be more pronounced the further away from the leg tip the measurement point was Maximal low-frequency amplification ranged from 8 to 32 dB, maximal mid-frequency attenuation between −7 and −33 dB, with higher values closer to the carapax The vibration transfer characteristics were essentially independent of the input amplitude over the biologically relevant intensity range (Fig 5) 4 When a train of input pulses was given at about the drumming rate of maleUca pugilator the transfer function changed during the train, with transmission of the first few impulses being as described above and that of later impulses being more ‘sharply tuned’, that is, with the low-frequency amplification range being narrower (Fig 6) This change in transmission is reproducibly accompanied by small active postural changes of the crab (‘alerting reaction’) 5 Animals resting in body-contact with the substrate rather than in an upright ‘alert’ stance showed very different transmission characteristics with much less modification of the signal between substrate and carapax (Fig 7) 6 These results are compared with the known spectral energy distribution of crab drumming signals It is concluded, that the described transmission characteristics of the crab leg emphasize the specific communication signals while at the same time damping noise vibrations

Degradation of collagen substrates by a trypsin-like serine protease from the fiddler crab Uca pugilator.

Abstract: The collagenolytic properties of a trypsin-like protease from the hepatopancreas of the fiddler crab Uca pugilator have been examined. All collagen types, I-V, were attacked by this enzyme. Types III and IV were degraded much more rapidly than types I, II, and V. Crab protease produced multiple cleavages in the triple helix of each collagen at 25 degrees C; only in the case of type III collagen, however, was a major cleavage observed at a 3/4:1/4 locus that corresponded to the region of collagen susceptibility to mammalian collagenase action. Additionally, both the affinity and the specific activity of the crab protease for native collagen were lower than those which characterize mammalian collagenase. The results of this study, in conjunction with a previous report on the collagenolytic activity of another serine protease from the fiddler crab [Welgus, H. G., Grant, G. A., Jeffrey, J. J., & Eisen, A. Z. (1982) Biochemistry 21, 5183], suggest that the following properties distinguish the action of these invertebrate collagenolytic enzymes from the metalloenzyme collagenases of mammals: (1) broad substrate specificity, including both noncollagenous proteins and collagen types I-V; (2) ability to cleave the native triple helix of collagen at multiple loci; (3) reduced affinity or higher Km for collagen; and (4) lower specific activity on collagen fibrils.

Genetics and evolution of the hemocyanin multigene—I. Genetic variability in UCA pugilator from beaufort, NC

Abstract: 1. 1. Hemocyanin from Uca pugilator is a polymer of peptides coded for by 6 distinct loci. 2. 2. Naturally occurring allelic variation provides evidence that 4 of these loci may be located on a single chromosome. 3. 3. A model for the evolution of an arthropodan hemocyanin multigene is presented based on genetic and biochemical data.

Cycle: a histochemical study of the fiddler crab,

Abstract: Histochemical data support the previous biochemical finding that the blood is a major site for the production of proteinaceous and diphenolic substances for tanning ofthe cuticle in the fiddler crab, Uca pugilator. Five types ofhemocytes are described. Specifically in tanning, the hyaline cells (cystocytes) appear responsible for the pro duction ofdiphenolic tanning agents whereas the granulocytes synthesize the proteins involved. Other types of hemocyte may be transitional forms involved in clotting (intermediate cells). Various histochemical reactions for each type of hemocyte and the cuticle are recorded throughout the molting cycle, and appear cyclic. The data suggest there is hormonal control of the cyclic events during the tanning process.